The Cboe Volatility Index— or VIX — spiked 84% on the day, its biggest single-day increase of all time, according to data going back to 1990.

That's good news for the world's fastest traders, which benefit when there's market chaos.

Virtu, the high-speed trading firm, was one of the few firms to finish Monday in the green.

The world's fastest traders must be loving this.

The Dow Jones Industrial Average witnessed its largest point decline in over six years on Monday, while the VIX - an index that gauges market anxiety - soared to its highest level since 2015, doubling in the span of a few hours.

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This development gives high-speed traders a reason to cheer.

High-frequency traders have seen revenues decline for years, and historically low volatility of the past year has led to a breaking point.

As liquidity providers, HFTs are scanning the markets for opportunities in which buyers and sellers aren't matched up. But when volatility is too low, like it was for much of 2017 and early 2018, those opportunities are hard to come by because there are fewer price swings.

"Greater volatility means a greater demand for liquidity and higher liquidity premiums (spreads) and that is what market makers sell," Larry Tabb, the founder of TABB Group, told Business Insider in an email. "When the demand and price of liquidity increases, market makers usually make money."

As such, Monday's volatility surge is good news for HFTs and market making firms, according to Dave Weisberger, the head of equities at ViableMkts, a market structure technology company.

"Today's intraday volatility is good for market makers and proprietary trading firms including those that have invested in HF infrastructures," Weisberger said.

Critically for these firms, there's a good chance that this bout of volatility is the first of many, according to strategists.

John Normand, head of cross-asset fundamental strategy at JPMorgan, said in a note that his base case was that inflation surprises become more frequent over the next six months, and that "these surprises generate recurring spikes in market volatility due to extreme valuations and investor positions in almost every asset class (only commodities are not expensive, and only the yen is under-owned."

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Virtu Financial, one of the largest high-frequency trading firms, appears to be benefiting from the market chaos. Despite the Dow's near 1,200 point decline, Virtu's stock was in the green at $19.43 a share, according to Markets Insider data.

"Well if you look at Virtu, they are one of the few stocks up on the day," Richard Johnson of Wall Street consultancy Greenwich Associates told Business Insider. "That's a sign that this is good for them."

The company's chief executive officer Douglas Cifu has referred to the period of low volatility as a "terrible environment" for the firm. During a fourth quarter earnings call, Cifu said he's "really excited about when - not if but when - volatility comes back."